Rotor for V8 Outboard Motor – Fits Mercury & OMC (Replaces 13524A1, 13524A5, 13524T1)

$13.49

Shipping calculated at checkout.

Worry-free returns

You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).

You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).

If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.

Delivery and Shipping

Free standard shipping on all orders under 1 KG

If you have any questions, feel free to email us at info@sierramarines.com, and we’ll get back to you within 20–36 hours.

Product Details

This high-quality Rotor for V8 Outboard Motor is engineered for reliable ignition performance in Mercury/Mercruiser V8 engines with Thunderbolt ignition (1981–2001) and various OMC V8 models. It serves as a direct-fit replacement to restore spark timing and engine efficiency.

It interchanges with a wide range of part numbers, including Sierra 18-5431, Mallory 9-29200, and multiple OEM numbers from Mercury and OMC.

Designed for direct, hassle-free installation.
Built to withstand harsh marine environments.
Includes one complete rotor assembly.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Brand	Part Number
Sierra Marine	18-5431 / 18-5431D
Mallory Marine	9-29200
Mercury	13524A1 / 13524A5 / 13524B1 / 13524B5 / 13524T1 / 19021A2 / 42862 / 805759Q3 / 805759T1 / 805759T3 / 805759T6 / 905741
OMC	0503026 / 0503211 / 0775439 / 0775514

Engine & Model Compatibility

Confirm your engine model/year in the table below.

For Mercury/Mercruiser, this rotor fits V8 models from 1981–2001 equipped with the Thunderbolt ignition system.

For OMC, this part is compatible with select V8 engines. Verify your OEM part number against the cross-reference list.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.	Notes
Mercury/Mercruiser	V8 with Thunderbolt Ignition	Various	4-Stroke	1981–2001	13524A1, 13524A5, 13524T1	Multiple supersessions
OMC	V8 Models	Various	4-Stroke		0503026, 0503211, 0775439, 0775514

Technical Specs

Product Type: Ignition Rotor Assembly
Installation: Direct replacement
Housing Color: Black
Dimensions (L x W x H): 10.0 x 8.5 x 10.0
Weight: 0.85 kg (1.87 lb)
System Compatibility: For V8 engines with Thunderbolt ignition system

What’s in the Box

1 x Rotor Assembly

Installation Notes

Disconnect the boat's battery for safety.
Locate the distributor and unclip or unscrew the distributor cap. Move it aside without disconnecting the spark plug wires.
Take note of the direction the old rotor is pointing before removal.
Pull the old rotor straight up off the distributor shaft. It may require a firm tug.
Align the new rotor with the shaft (it is often keyed to fit only one way) and press it down firmly until it is fully seated.
Inspect the distributor cap terminals for wear or corrosion before reinstalling it.
Secure the distributor cap and reconnect the battery terminals.

Troubleshooting & FAQ

How do I know if this rotor fits my engine?

This rotor fits specific Mercury/Mercruiser V8 engines (1981–2001) with Thunderbolt ignition and certain OMC V8s. The best way to confirm is to match your old part number to the equivalents listed in our Part Number Matrix. Verifying fitment before purchase is essential.

What are the signs of a failing ignition rotor?

Common symptoms include engine misfires, rough idling, difficulty starting, stalling, or a noticeable drop in engine performance and fuel efficiency. Visual inspection of your old rotor may reveal cracks, burn marks, or corrosion on the metal contact.

How often should I replace my ignition rotor?

For preventative maintenance, it is recommended to inspect your ignition rotor and distributor cap annually. We suggest replacing it if you see any signs of wear or damage, or as part of a regular tune-up schedule based on your engine's service hours.

Is this rotor different from the OEM part?

This is an aftermarket part designed to meet or exceed original equipment manufacturer (OEM) specifications for fit, form, and function. It provides the same performance and reliability as the original at a better value.

OEM vs. Aftermarket?

This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.

Shipping speed & cost

We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.

Warranty & returns

Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.

Safety & Important Info

Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
This is an aftermarket replacement, not an OEM component.
Professional installation is recommended for safety and performance.

About Sea Sierra

Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.

Payment & Security

Payment methods

Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.